This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/JP98/05448 which has an International filing date of Dec. 3, 1998 which designated the United States of America.
1. Technical Field
This invention relates to a crane system which has a wire rope stretched from a frame of a body to a hoisting accessory, and which pays out the wire rope from a drum or winds the wire rope around the drum to carry a load transversely, or move it up or down.
2. Related Art
A crane system for carrying a container (load) is present in a place such as a container yard at a port. The crane system is used to unload containers from a vehicle or the like and stack them on the container yard, or load containers from the container yard into a vehicle or the like.
FIG. 1 shows an example of a gantry crane system which has existed so far. This type of crane system has a pair of gate-shaped body frames, i.e., front and rear body frames 101. The crane system includes a plurality of traveling wheels 103 provided at a lower end of each of legs 101a for supporting a transverse girder 101b of each of the body frames 101, and traction motors 102 for driving the traveling wheels 103. The traction motor 102 rotationally drives the traveling wheels 103, thereby moving the body frames 101 in a front-and-back direction (a direction along the front and the back of the body frames 101 disposed at the front and at the back, respectively; the same will hold hereinbelow).
On the front and rear transverse girders 101b of these body frames 101, rails 104 are laid. The front and rear rails 104 and 104 as a pair are spanned by a traversing trolley 105, which is supported on the rails laterally movably.
On the traversing trolley 105, a takeup drum 106 is borne. The takeup drum 106 is wound with a plurality of wire ropes 107 for suspending a load, and a hoisting accessory 108 is suspended via these plural wire ropes 107. A container C as a suspended load is attached to the hoisting accessory 108.
The conventional crane system of the foregoing constitution carries the container C in the following manner: As shown in FIG. 2 as well, with the body frames 101 at a halt, the hoisting accessory 108 is lowered, and the container C is attached to the hoisting accessory 108. Then, the takeup drum 106 is driven to wind the wire ropes 107, thereby moving the hoisting accessory 108 upward. As a result, the container C is raised and suspended. Then, the traversing trolley 105 is moved in a traversing direction (a direction of an arrow A in FIG. 2 in which a traversing motion is made rightward or leftward on the gate-shaped body frames 101; the same will hold hereinbelow) along the rails 104, whereby the container C is moved to a predetermined position.
Once the container C arrives at the predetermined position, the traversing trolley 10S is stopped. In this state, the wire ropes 107 are paid out by driving the takeup drum 106 to move the hoisting accessory 108 vertically downward (in a direction of an arrow C in FIG. 2), thereby lowering the container C. The container C is placed at a predetermined position as shown by a two-dot chain line in FIG. 2.
With this conventional crane system, it is necessary to provide the rails 104 on the transverse girders 101b of the body frames 101, and install the traversing trolley 105 on these rails 104. In this case, there is need to consider the weight of the rails 104, the weight of the traversing trolley 105, and the weight of the container C imposed on the hoisting accessory 108. Thus, not only the transverse girders 101b, but also the entire crane system must have great rigidity and large weight.
In the crane system illustrated in FIG. 1, consider that with the container C being held by the hoisting accessory 108, the traversing trolley 105 is moved laterally (horizontally) along the rails 104, and stopped at a predetermined position. In this case, sway in a direction of an arrow B in FIG. 2 occurs in the hoisting accessory 108 and the container C owing to the inertial force of the traversing trolley 105 moving in the lateral direction. This sway often does not settle quickly.
Actually, therefore, the traversing trolley 105 is moved at a low speed so that no sway occurs in the hoisting accessory 108 and the container C when the traversing trolley 105 is stopped. If such sway takes place, the operator waits until settlement of the sway, and then the wire ropes 107 are paid out from the takeup drum 106 to lower the container C.
This practice of moving the traversing trolley 105 at a low speed, or resuming operation after waiting until settlement of the sway of the hoisting accessory 108 and the container C, takes a long time for operation, thus deteriorating the operating efficiency.
There may be a case in which a load handling operation is performed on a floor FL inclined to drain rainwater or the like, as shown in FIG. 3. In this case, with the crane system of FIG. 1, the body frames 101 become inclined according to the slope of the floor FL. Nevertheless, the hoisting accessory 108 and the container C, attached to the traversing trolley 105 via the plurality of wire ropes 107, are suspended vertically, in other words, obliquely relative to the floor FL, by their own weight.
Then, it is attempted to lower and place the container C at a predetermined position indicated by a two-dot chain line in FIG. 3. However, the container C held by the hoisting accessory 108 may touch a container C nearby, depending on the number of containers C stacked or the distance between the adjacent stacks of containers C. This may make it difficult to place the suspended container C exactly at the predetermined position.
FIG. 4 shows a wire rope crane at a port, proposed by the applicant, for loading onto a ship or unloading from a ship onto the land. This crane system in FIG. 4 has a relay yard 120 for the efficient carriage of a container C. Between the relay yard 120 and a floor FL of a container yard, wire ropes 122 stretched between a hoisting accessory 108 and hoists 121, which are disposed at upper right and upper left positions, are extended and contracted. By this measure, the container C is carried between the relay yard 120 and the floor FL. There is a disclosure that the rightward and leftward wire ropes 122 are connected to the hoisting accessory 108 at its one or two (including another in the depth direction) connection points P.
This proposal shown in FIG. 4 has a structure in which the hoisting accessory 108 is suspended by the wires 121 from obliquely upward sites. This structure permits anti-sway of the portion 122 corresponding to the wire rope up to the connection point P in the aforementioned crane system shown in FIGS. 1 to 3. Thus, the hoisting accessory 108 and the container C may be prevented from swaying, and drawbacks due to the aforesaid low-speed movement or lengthy time until settle of sway may be diminished.
For the rope crane of FIG. 4, the relevant structure has been disclosed, but there have been no disclosures of problems encountered during actual operation, such as the weight and rigidity of the crane, control for each of the delivery and winding of the wire 122, and difficulty with the placement of a container on the slope of the floor FL. What has been disclosed is only the crane system using the wires 122.
The present invention has been accomplished in light of the foregoing problems. An object of the invention is to provide a crane system in which wire ropes are pulled obliquely upwardly to suspend a hoisting accessory, and wire rope actions for traversing and hoisting/lowering of the hoisting accessory are coordinated for actual operation.
It is another object of the invention to provide a crane system of a downsized, simplified structure which has diminished the great rigidity and heavy weight of a conventional crane.
It is still another object of the invention to provide a crane system which has further ensured the anti-sway of a suspended load such as a container.
It is a further object of the invention to provide a crane system capable of favorably stacking a suspended load, such as a container, even when a floor surface is inclined.
A crane system according to the present invention comprises a body frame; a hoisting accessory provided with a connection point; a wire rope winding/unwinding drum attached to the body frame; sheaves attached to both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a first wire rope attached at one end to the connection point, and passed at the other end round the drum via the sheave located at one of the ends; a second wire rope attached at one end to the connection point, and passed at the other end round the drum via the sheave located at the other end in a direction opposite to the direction of the first wire rope; and means attached to the body frame for moving the drum in a direction in which the hoisting accessory ascends or descends.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with a connection point; a wire rope winding/unwinding drum attached to the body frame; sheaves attached to both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a first wire rope attached at one end to the connection point, and passed at the other end round the drum via the sheave located at one of the ends; a second wire rope attached at one end to the connection point, and passed at the other end round the drum via the sheave located at the other end in a direction opposite to the direction of the first wire rope; a first movable pulley wound with the first wire rope located between the drum and the sheave at the one end; a second movable pulley wound with the second wire rope located between the drum and the sheave at the other end; and means attached to the body frame for moving the first and second movable pulleys in a direction in which the hoisting accessory ascends or descends.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with a connection point; a wire rope winding/unwinding drum attached to the body frame; sheaves attached to both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a first wire rope attached at one end to the connection point, and passed at the other end round the drum via the sheave located at one of the ends; a second wire rope attached at one end to the connection point, and passed at the other end round the drum via the sheave located at the other end in the same direction as the direction of the first wire rope; and means attached to the body frame for moving the drum in a direction in which the hoisting accessory traverses.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with a connection point; a wire rope winding/unwinding drum attached to the body frame; sheaves attached to both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a first wire rope attached at one end to the connection point, and passed at the other end round the drum via the sheave located at one of the ends; a second wire rope attached at one end to the connection point, and passed at the other end round the drum via the sheave located at the other end in the same direction as the direction of the first wire rope; a first movable pulley wound with the first wire rope located between the drum and the sheave at the one end; a second movable pulley wound with the second wire rope located between the drum and the sheave at the other end; and means attached to the body frame for moving the first and second movable pulleys in a direction in which the hoisting accessory traverses.
Thus, the wire ropes are stretched obliquely upwardly relative to the hoisting accessory. Because of a restraining force due to the horizontal tension of the wire ropes, sway of the hoisting accessory or a suspended load can be suppressed effectively. Furthermore, it is not necessary to consider the weight of the trolley or the weight of the transverse girders, or to give great rigidity to the transverse girders, as in the case of a conventional crane system. Basically, it suffices to support only the weights of the wire ropes, the hoisting accessory, and the suspended load. By so doing, a marked weight decrease can be achieved, and downsizing and simplification of the structure can be realized. Besides, the rope crane can be simplified and downsized because of decreased weight and rigidity, and preferred control of the suspended load can be attained through coordination between traversing and hoisting/lowering due to driving of the drum.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with a connection point; a wire rope winding/unwinding drum attached to the body frame, and having two input shafts and two output shafts, the output shafts being rotatable in the same direction responsive to input from one of the shafts, and being rotatable in opposite directions responsive to input from the other shaft; sheaves attached to both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a first wire rope attached at one end to the connection point, and passed at the other end round one of the output shafts of the drum via the sheave located at one of the ends; and a second wire rope attached at one end to the connection point, and passed at the other end round the other output shaft of the drum via the sheave located at the other end.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with a connection point; a pair of first sheaves installed at the connection point; a wire rope winding/unwinding drum attached to the body frame, and having two input shafts and two output shafts, the output shafts being rotatable in the same direction responsive to input from one of the shafts, and being rotatable in opposite directions responsive to input from the other shaft; second sheaves attached to both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a first wire rope attached at one end to one end, in the traversing direction, of an upper surface of the body frame, and passed at the other end round one of the output shafts of the drum via one of the first sheaves and the second sheave provided on a side where the one end of the first wire rope has been attached; and a second wire rope attached at one end to the other end, in the traversing direction, of the upper surface of the body frame, and passed at the other end round the other output shaft of the drum via the other first sheave and the second sheave provided on a side where the one end of the second wire rope has been attached.
Thus, the constituent drums can be easily rotationally driven in the same direction and in opposite directions by the wire rope winding/unwinding drum mechanism. Hence, a traversing and hoisting/lowering action can be performed by operation of a single driving unit. In addition, electric power consumption of the motor can be decreased regardless of the position of the suspended load.
According to the crane system of the present invention, wire rope length adjusting means may be provided between the connection point and the first wire rope and/or between the connection point and the second wire rope. Alternatively, wire rope length adjusting means may be provided between the body frame and the first wire rope and/or between the body frame and the second wire rope.
According to the crane system of the present invention, the drum is provided with taper portions; and the first and the second wire ropes are passed round the taper portions so that when tensions on the first and second wire ropes equal, portions of the first and second wire ropes passed round the drum have the same diameter, and when tensions on the first and second wire ropes do not equal, a portion of the wire rope passed round the drum and undergoing the higher tension has a smaller diameter, while a portion of the wire rope passed round the drum and undergoing the lower tension has a larger diameter.
Thus, no imbalance occurs in the ways of winding or in the diameters of the wound ropes on the drum, so that uniform load is imposed. Even if the hoisting accessory leans rightward or leftward in the traversing direction, torques acting on the drum are counterbalanced.
According to the crane system of the present invention, a second hoisting accessory following the aforementioned hoisting accessory and capable of ascending and descending relative to that hoisting accessory is provided below that hoisting accessory. By moving the lower hoisting accessory upward or downward relative to the upper hoisting accessory, interference by the obliquely upward wire rope is prevented. Thus, unloading onto a ship""s hold, for example, can be performed without a hitch.
According to the crane system of the present invention, various modifications are available, such as the installation of the drum and the movable pulley moving means on an upper beam constituting the body frame, the installation of the drum and the drum moving means on the upper beam constituting the body frame, and the installation of the drum on the upper beam constituting the body frame.
The crane system of the present invention may have a constitution in which the aforementioned connection points are provided at four sites at the four corners of the hoisting accessory, and two of the sheaves corresponding to the connection points are attached to each of the four corners of the body frame; and may also have a constitution in which the connection points where the first sheaves are installed are provided at four sites at the four corners of the hoisting accessory, and two of the second sheaves corresponding to the first sheaves are attached to each of the four corners of the body frame. Thus, the anti-sway of the suspended load by the wire ropes can be further improved, and the posture of the suspended load can be controlled.
The crane system of the present invention may have a constitution in which a group of the first wire ropes and a group of the second wire ropes stretched between the connection points at the four sites and the corresponding sheaves are parallel to the traversing direction when viewed as a plan view, or may have a constitution in which a group of the first wire ropes and a group of the second wire ropes stretched between the body frame and the first sheaves and between the first sheaves and the corresponding second sheaves are parallel to the traversing direction when viewed as a plan view.
According to the crane system of the present invention, the length of the hoisting accessory in a direction perpendicular to the traversing direction is made greater than the length of the suspended load, whereby interference with stacked cargo by the hoisting accessory or the wire ropes can be prevented.
According to the crane system of the present invention, the group of the first wire ropes stretched from the connection points arranged at two sites in the traversing direction to the corresponding sheaves are parallel and of the same length when viewed as a vertical cross sectional view perpendicular to the traversing direction, and the group of the second wire ropes stretched from the connection points arranged at two sites in the traversing direction to the corresponding sheaves are parallel and of the same length when viewed as a vertical cross sectional view perpendicular to the traversing direction. Alternatively, the group of the first wire ropes stretched from the first sheaves arranged at two sites in the traversing direction to the corresponding second sheaves are parallel and of the same length when viewed as a vertical cross sectional view perpendicular to the traversing direction, and the group of the second wire ropes stretched from the first sheaves arranged at two sites in the traversing direction to the corresponding second sheaves are parallel and of the same length when viewed as a vertical cross sectional view perpendicular to the traversing direction. Thus, a group of adjacent parallel wire ropes of the plurality of wire ropes can be controlled to be taken up or paid out as a single unit, so that control can be simplified.
According to the crane system of the present invention, the connection points are movable so as to extend or contract in a direction perpendicular to the traversing direction, and the sheaves are movable so as to extend or contract in a direction perpendicular to the traversing direction. Alternatively, the connection points are movable so as to extend or contract in a direction perpendicular to the traversing direction, and portions of the first wire rope and the second wire rope mounted on the body frame, and the second sheaves are movable so as to extend or contract in a direction perpendicular to the traversing direction. Thus, even if the size of the suspended load changes, the changed size can be accommodated.
According to the crane system of the present invention, means for turning the hoisting accessory in a horizontal plane is provided. Thus, even if there is misalignment or the like of the suspended load, the suspended load can be hoisted or lowered without moving the entire crane system.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with connection points at four sites at four corners; wire rope winding/unwinding drums attached to both ends, in a traversing direction, of an upper surface of the body frame; a group of first wire ropes attached at one end to the connection points, and passed at the other end round the drum located at one of the ends in the same direction for all the wire ropes; and a group of second wire ropes attached at one end to the connection points, and passed at the other end round the drum located at the other end in the same direction for all the wire ropes.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with connection points at four sites at four corners; sheaves attached to both ends, in a traversing direction, of an upper surface of the body frame; a first wire rope winding/unwinding drum attached to the body frame; a second wire rope winding/unwinding drum attached to the body frame; a group of first wire ropes attached at one end to the connection points, and passed at the other end round the first drum via the sheave located at one of the ends in the same direction for all the wire ropes; and a group of second wire ropes attached at one end to the connection points, and passed at the other end round the drum via the sheave located at the other end in the same direction for all the wire ropes.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with a connection point; a pair of first sheaves installed at the connection point; a first wire rope winding/unwinding drum attached to the body frame; a second wire rope winding/unwinding drum attached to the body frame; second sheaves attached to both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a first wire rope passed at one end round the first drum, and passed at the other end round the second drum via the second sheave located at one of the ends and via one of the first sheaves; and a second wire rope passed at one end round the first drum in the same direction as the direction of the first wire rope, and passed at the other end round the second drum via the second sheave located at the other end and via the other first sheave in a direction opposite to the direction of the first wire rope.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with a connection point; a pair of first sheaves installed at the connection point; a wire rope winding/unwinding drum attached to the body frame, and having two input shafts and two output shafts, the output shafts being rotatable in the same direction responsive to input from one of the shafts, and being rotatable in opposite directions responsive to input from the other shaft; a pair of second sheaves attached to each of both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a first wire rope attached at one end to one end, in the traversing direction, of an upper surface of the body frame, and passed at the other end round one of the output shafts of the drum via one of the second sheaves provided on a side where the one end of the first wire rope has been attached, one of the first sheaves, and the other second sheave provided on the side where the one end of the first wire rope has been attached; and a second wire rope attached at one end to the other end, in the traversing direction, of the upper surface of the body frame, and passed at the other end round the other output shaft of the drum via one of the second sheaves provided on a side where the one end of the second wire rope has been attached, the other first sheave, and the other second sheave provided on the side where the one end of the second wire rope has been attached.
Another crane system according to the present invention comprises a body frame; a hoisting accessory provided with connection points at four sites at four corners; a pair of first sheaves installed at each of the connection points; a first wire rope winding/unwinding drum attached to the body frame; a second wire rope winding/unwinding drum attached to the body frame; a pair of second sheaves attached to each of both ends, in a hoisting accessory traversing direction, of an upper surface of the body frame; a group of first wire ropes attached at one end to one end, in the traversing direction, of the upper surface of the body frame, and passed at the other end round the first drum in the same direction for all the wire ropes via one of the second sheaves provided on a side where the one end has been attached, one of the first sheaves, and the other of the second sheaves provided on the side where the one end has been attached; and a group of second wire ropes attached at one end to the other end, in the traversing direction, of the upper surface of the body frame, and passed at the other end round the second drum in the same direction for all the wire ropes via one of the second sheaves provided on a side where the one end has been attached, the other of the first sheaves, and the other of the second sheaves provided on the side where the one end has been attached.
According to the crane system of the present invention, the connection points where the first sheaves are installed are provided at four sites at the four corners of the hoisting accessory, the second sheaves corresponding to the first sheaves are provided parallel at two sites each in the traversing direction at both ends of two transverse girders of the body frame, and mounting portions, at one end, of the first and second wire ropes are opposite end portions of the two transverse girders of the body frame.
According to the crane system of the present invention, the drums are placed at the middle of the two transverse girders such that the shaft center of one of the output shafts and the shaft center of the other output shaft are arranged parallel in the traversing direction, two of the first wire ropes passed from the second sheaves at the two sites on one end side of each of the two transverse girders and wound round one of the output shafts of the drum placed on the same transverse girder are wound symmetrically with respect to a line passing through the center of the length of the one output shaft, two of the second wire ropes passed from the second sheaves at the two sites on the other end side of each of the two transverse girders and wound round the other output shaft of the drum placed on the same transverse girder are wound symmetrically with respect to a line passing through the center of the length of the other output shaft, and the first wire ropes and the second wire ropes wound round the output shafts are symmetric with respect to a line passing through the center of the length of each of the transverse girders.
Where necessary, any of the above-described constitutions may be modified in any of the foregoing modes designed for anti-sway, downsizing and structure simplification by weight reduction, and so forth.
According to the crane system of the present invention, the crane may be a container crane, the connection point or connection points may be provided directly on a suspended load as a replacement for the hoisting accessory, the body frame may be mobile, and the body frame portion supporting the transverse girders may be a building.
The present invention also concerns a method for manipulating the position of a hoisting accessory of a crane, which comprises providing connection points at four sites at the four corners of the crane; stretching a first wire rope from each of the connection points toward one end, in a hoisting accessory traversing direction, of an upper surface of a crane body frame; stretching a second wire rope from each of the connection points toward the other end, in the hoisting accessory traversing direction, of the upper surface of the crane body frame; taking up one of the first and second wire ropes and paying out the other of the first and second wire ropes to make the hoisting accessory mainly traverse; and taking up or paying out both of the first and second wire ropes to make the hoisting accessory mainly ascend or descend.
These and other objects of the present application will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.